Amphoteric surface-active compounds of many different types have been utilized in washing agent compositions. They are of particular interest for use in hair shampoo formulations due to their low irritation to the eyes. It has been found that the products based on diamines have the least effect on the conjunctiva.
Products based on diamines, however, are often described as having an imidazoline ring, as for example, U.S. Pat. No. 3,849,315. In this patent imidazoline surfactants are disclosed having the formulae ##STR2## However, such imidazoline structures are actually difficult to obtain since, in the presence of water, they readily hydrolyze to give a linear structure ##STR3## Such products are sold under the trademark Miranol.RTM.. Such products, however, gradually break down in both alkaline and acidic solutions forming, over a period of time, turbidity in their solutions.
In addition, other types of compounds based on diamines, which have surface-active properties, have been disclosed. For example, U.S. Pat. No. 2,927,901 discloses compounds of the formula ##STR4##
U.S. Pat. No. 2,993,918 discloses compounds of the formula ##STR5##
U.S. Pat. No. 3,813,422 discloses compounds of the formula ##STR6## and U.S. Pat. No. 3,888,797 discloses compounds of the formula ##STR7## These compounds, however, readily break down where the amide link ##STR8## is present, or are not sufficiently hydrophillic in the presence of only one hydroxyl or ether group.